Also, Ridley Scott spoke to Movies.com and was very open about discussing specifics about the Engineers. Here are a few excerpts:

So I always had it in there that the God-like creature that you will see actually is not so nice, and is certainly not God. As she says, “This is not what I thought it was going to be, and I think we should get the Hell out of here or there won’t be any place to go back to.”

Thats not necessarily planted in the ground at the tail end of the third act, but I knew thats kind of where we should go, because if we’ve opened up this door — which I hope we have because I certainly would like to do another one  I’d love to explore where the hell [Dr. Shaw] goes next and what does she do when she gets there, because if it is paradise, paradise can not be what you think it is. Paradise has a connotation of being extremely sinister and ominous.

When asked about how he planned to approach the film to pull audiences in, Scott spoke about the beginning of the film: “I was hoping I had with the fact that you have a sequence at the beginning of the film that is fundamentally creation. Its a donation, in the sense that the weight and the construction of the DNA of those aliens is way beyond what we can possibly imagine.”